Downhole Tool Roller Device With Cylindrical Bearing Mechanism

ABSTRACT

Roller devices for passively or actively aiding in the conveyance of a toolstring through a well. The well may be of tortuous architecture and include a host of different corrosives. However, the roller devices are equipped with a cylindrical bearing based mechanism such as a journal bearing. Thus, these devices may be substantially less prone to exposure to corrosives. For example, they may be provided in a substantially monolithic circumferential form more readily shielded and/or isolated from such direct exposure.

PRIORITY CLAIM/CROSS REFERENCE TO RELATED APPLICATION(S)

This Patent Document claims priority under 35 U.S.C. § 119 to U.S. Provisional App. Ser. No. 61/613,261, entitled “Conveyance Accessories” filed on Mar. 20, 2012, and incorporated herein by reference in its entirety.

BACKGROUND

Exploring, drilling and completing hydrocarbon and other wells are generally complicated, time consuming and ultimately very expensive endeavors. In recognition of these expenses added emphasis has been placed on maximizing each given well's life and productivity over the course of the well's life. Thus, well logging, profiling and monitoring of well conditions are playing an ever increasing role in oilfield operations. Similarly, more actively interventional applications are regularly called for such as clean-out applications, opening or closing valves and sliding sleeves or any number of other maneuvers targeting maximized recovery and well life.

In addition to regular intervention for sake of monitoring and/or managing well operations, the well itself may also be of fairly sophisticated architecture. For example, in an attempt to maximize recovery from the reservoir and extend the useful life of the well, it may be of a fairly extensive depth and tortuous configuration. This may include overall depths in the tens of thousands of feet range. Once more, such wells may include extended horizontal or deviated sections of several thousand feet. As a result, interventions through such wells are becoming of ever increasing difficulty as noted below.

Where interventional applications are sought in wells of particularly challenging architecture, wireline cable, coiled tubing, drill pipe or other semi-rigid conveyance line may be utilized to deliver an interventional tool to a target location in the well. In order to help the conveyance line navigate the well downhole, conveyance aids are available to help the conveyance line and toolstring traverse the challenging architecture of the well. These may include active conveyance aids such as tractors or vibration tools, generally located near the end of conveyance line near the toolstring. Thus, the conveyance line may be actively pulled further downhole or vibrated in such a manner as to help extend the overall reach of the conveyance line.

In light of the potential drawbacks to conveyance aids noted above, a toolstring may be outfitted with more straight-forward, passive features to help in traversing a well of sophisticated architecture. For example, the toolstirng or a housing of a given tool may be equipped with passive rollers. That is, conventional, appropriate sized wheel-like features may be placed at the outer surface of the toolstring. So, for example, where a 100 foot toolstring is rounding a transition bend of a few hundred feet or so into a deviated well section, the rollers may passively contact the well wall as the bend is rounded. This may prevent mechanical or even differential sticking in such situations. Once more, preventing such sticking in this manner may be the extent of the conveyance aid that is required in order to allow the tool to reach the target location downhole. That is, the challenge in delivering the toolstring to the downhole target location at times may be less about overall load capacity throughout the well, for example, as may be met by a heavy duty tractor, and more about being able to passively round a bend at a given location. Certainly where this is the case, passive roller-aided conveyance may be preferable to other aiding techniques.

Unfortunately, while passive roller-aided conveyance may be suitable for helping the toolstring to reach a downhole target location in theory, rollers face their own inherent limitations. For example, passive, and even active rollers, generally include bearing ring assemblies similar to those found in wheels on conventional pair of roller skates. Setting aside manufacturability disadvantages, these types of assemblies are also relatively short-lived upon exposure to downhole environments. That is, it is understandable that a host of spherical bearings exposed to debris, sand or downhole fluids tends to lock-up and/or corrode fairly quickly. Indeed, after every couple of deployments into the well, it is likely that replacement of all of the bearing assemblies for the toolstring is called for. Yet, in spite of these added maintenance and materials costs, this is often the operators' most practical option for aiding in the conveyance of the toolstring.

SUMMARY

A downhole toolstring is provided that includes a tool housing equipped with a conveyance aid. The conveyance aid includes at least two roller devices for contacting a wall of the well during the conveyance therethrough. Further, the roller devices themselves each include a cylindrical bearing based mechanism to allow rolling thereof during the contacting of the wall.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overview of an oilfield with a well that accommodates a toolstring employing embodiments of roller devices as a conveyance aid.

FIG. 2A is an enlarged side view of the toolstring of FIG. 1 and highlighting the roller devices thereof.

FIG. 2B is a front cross sectional view of the toolstring taken from line 2-2 of FIG. 2A revealing the internal working of a given roller device.

FIG. 3A is a side view of the underside of a roller device of FIGS. 1, 2A and 2B highlighting an embodiment of a journal bearing therein.

FIG. 3B is a side view of an alternate embodiment of the journal bearing of FIG. 3A.

FIG. 4A is a side view of the toolstring of FIG. 1 employing an alternate embodiment of roller devices as a conveyance aid.

FIG. 4B is a front cross sectional view of the toolstring taken from line 4-4 of FIG. 4A revealing the internal working of a given roller device.

FIG. 5 is a flow-chart summarizing an embodiment of employing roller devices of a toolstring as an aid to conveyance thereof through a well.

DETAILED DESCRIPTION

Embodiments are described with reference to certain downhole applications through deviated well sections that may benefit from roller devices as an aid to conveyance of a toolstring through the well. In particular, coiled tubing line is utilized to deliver a logging and treatment assembly of considerable length to a downhole location at a depth beyond a non-vertical section of the well. Though, wireline, drill pipe and other conveyance line types may be utilized. Regardless, conveyance of the assembly may be aided by passive rollers thereof as it enters a deviated or tortuous portion of the non-vertical well section. Of course, a host of other downhole assemblies and accessories, conveyed by coiled tubing or otherwise, may be outfitted with conveyance aids as detailed herein. These may include more interventional devices and applications such as for perforating or those of a more passive nature such as for more limited conventional logging. Regardless, so long as the conveyance aid of the assembly includes roller devices with cylindrical bearing based mechanisms therein, enhanced conveyance thereof through the well may be achieved.

Referring now to FIG. 1, an overview of an oilfield 105 is shown accommodating a well 180. The well 180 in turn accommodates a toolstring 101 that employs embodiments of roller devices 100 as a conveyance aid. That is, as is increasingly the case, the well 180 may be of somewhat sophisticated and non-vertical architecture, traversing several thousand feet and multiple formation layers 190, 195.

Thus, in the depicted example, where the toolstring 101 is conveyed to sufficient depths, it must traverse a bend 197 in the well 180. Given that the toolstring 101 may be a fairly rigid structure spanning 50-150 feet or more, roller device or devices 100 such as those depicted may serve as a passive aid in allowing the toolstirng 101 to round the bend 197. That is, as the rigid toolstring 101 is advanced by conveyance line such as, but not limited to, coiled tubing 110 into the bend 197, the well wall 185 may present a tight fit or squeeze to the elongated toolstring 101. However, the roller devices 100 may passively and responsively roll against the well wall 185 at this time to further aid in conveyance of the toolstring 101 beyond the bend 197.

While rounding the bend 197 with passive assistance of roller devices 100 appears fairly straight forward, particular challenges may be presented to the effectiveness of the devices 100 due to the nature of the well environment. For example, as detailed further below, the toolstring 101 of the example embodiment shown includes logging devices 160 for obtaining a variety of different types of well data such as the nature of the surrounding formation 195 or well fluids and other constituents. Indeed, as shown in FIG. 1, a significant amount of debris 199, sand or other particulate may be found in the well 180. These types of physical corrosives are not limited to isolated locations but are disbursed throughout the well 180 and fluids thereof. As a result, roller devices 100 as shown are fully exposed to such corrosives whenever positioned downhole. However, as detailed further below, the roller devices 100 are equipped with a unique cylindrical bearing based mechanism so as to minimize internal exposure and wear from the downhole environment, thereby extending life and effectiveness as a conveyance aid.

Continuing now with reference to FIG. 2A, with added reference to FIG. 1, an enlarged side view of the toolstring 101 is shown which highlights the noted roller devices 100. In this depiction it is apparent that the roller devices are of a profile that is slightly larger than the diameter (d) of the toolstring 101. Thus, as noted above, the roller devices 100 may passively contact the well wall 185 as needed (e.g. upon rounding the bend 197). As also indicated above, the toolstring 101 is conveyed via coiled tubing 110. In the embodiment shown, such operations may involve surface equipment 125 that includes use of a mobile coiled tubing truck 135 with reel 144 and control unit 142 for directing operations. These operations may include the conveyance of the coiled tubing 110 and toolstring 101 and/or directing of downhole applications as described further below. As will be appreciated by those skilled in the art, the conveyance line 110 may comprise wireline cable, slickline, coiled tubing, drill pipe, or any suitable conveyance line.

Continuing with reference to FIG. 1, conveyance includes routing the coiled tubing 110 and toolstring 101 through a gooseneck injector 155 at a rig 145 over the well 180. Thus, the entire assembly may be forcibly advanced through a blowout preventer 165 and into the vertical portion of the well 180. With added reference to FIG. 2A, the toolstring 101 may be advanced within the well 180 as described above for sake of logging and/or other downhole applications.

In the embodiment of FIG. 2A, the example toolstring 101 includes traditional logging as well as more interventional tool segments. For example, imaging 270, gas monitoring 230 and density acquisition 260 tools may constitute part of the logging device 160. However, a treatment tool 120 for delivering downhole fluids is also provided. In fact, the toolstring 101 is even outfitted with a sampling implement 265 for direct interfacing with the well wall 185 as described further below. That is, in the embodiment shown, the toolstring is not configured for use in an exclusively cased well or other more isolated environment. Rather, exposure by the toolstring 101 and its roller devices 100 to a host of downhole fluids, debris 199, introduced treatment fluids, and even formation disturbance is to be expected.

In light of the vast amount of particle and other expected downhole exposures, the roller devices 100 are configured with cylindrical bearing based mechanisms as noted above. More specifically, with reference to FIG. 2B, a front cross sectional view of the toolstring 101 is shown taken from line 2-2 of FIG. 2A. In this manner, the internal workings of a given roller device 100 are revealed. That is, apart from the internal density acquisition tool 261 and housing 260 at this portion of the logging device 160, two roller devices 100 are shown along with internals thereof.

The internals of the roller devices 100 reveal cylindrical bearing based mechanisms in the form of journal bearings 200. That is, the indicated housing 260 is equipped with mandrels 215 that extend therefrom such that circumferential, substantially monolithic journal bearings 200 may be disposed thereabout. In this manner, a smooth substantially uninterrupted bearing interface is provided between the body of each roller device 100 and each mandrel 215. As a result, exposure and opportunity for particulate, sand and other debris 199 of the well 180, to interact with such bearing based mechanisms 200 is kept at a minimum. For example, the amount of exposed surface to volume area is minimized with use of a smooth monolithic piece as opposed to conventional ball bearings. Furthermore, the ability is now afforded to configure the underside of a body of the roller device 100 to substantially morphologically match the journal bearing 200. Thus, the bearing 200 may be substantially isolated from the indicated exposures of concern.

Continuing with reference to FIG. 2B, the journal bearing 200 may be of a non-corrosive, durable metal so as to even further extend the life thereof. Additionally, the single-piece nature of the bearing 200 may afford ease of assembly and maintenance, even in circumstances where replacement is required. That is, hub screws 240 may be loosened for removal of a hub 210, and the single-piece bearing 200 dropped out of the roller device 100.

In the embodiment shown, two rollers 100 in an adjacent fashion. Thus, when a sampling implement 265 as shown in FIG. 2A is extended to interface with the well wall 185 (through zone 266), it may achieve a stable interface along a perpendicular axis 201. That is, the roller devices 100 may attain a foothold at one side of the well wall 185 and allow the implement 265 to achieve a largely sealed engagement with the opposite side of the well wall 185 for formation sampling therefrom. From a dimensional standpoint this may be achieved so long as the diameter of the well 180 sufficiently exceeds the width of the toolstring 101, from one 100 roller device to another roller device 100.

In the embodiment of FIG. 2B, the cylindrical bearing based mechanism is a journal bearing 200 as described. However, other forms of cylindrical bearing based mechanisms may alternatively be employed. For example, in one embodiment, cylindrical roller bearings may be utilized which provide a degree of both radial and axial slip. Additionally, as described further below with regard to FIGS. 4A and 4B, alternate embodiments of roller devices 400, 401 and journal bearing configurations may also be utilized.

Referring now to FIG. 3A a side view of the underside of a roller device 100 such as that of FIGS. 1, 2A and 2B is depicted. In this view, an embodiment of the journal bearing 200 is highlighted therein. The bearing 200 is of a circumferentially continuous and monolithic form as described above. Accordingly, it includes a continuous interior surface 315 for direct interface with a mandrel 215 as shown in FIG. 2B. Similarly, an exterior surface 301 is provided for interfacing the body of the roller device 100.

With added reference to FIG. 2B, the roller device 100 includes an exterior structure 350 and face 351 that is exposed to the well 180 for interfacing the well wall 185 as described above. However, it is also configured with a recess 375 having a portion for receiving the bearing 200. In the embodiment shown, this recess 375 is stepped down such that the bearing 200 does not occupy the entirety of the recess 375. Of course, in other embodiments, alternative recess architecture may be utilized.

Referring now to FIG. 3B, a side view of an alternate embodiment of the journal bearing 200 of FIG. 3A is shown. In the embodiment of FIG. 3B, the journal bearing 200 remains of continuous circumferential form. However, the bearing is split into separate monolithic pieces 320, 340 which are utilized together. More specifically, this results in the noted interior surface 315 and exterior surface 301 being associated with separate pieces 320, 340 of the bearing 200. As a result, forces that are exerted on the interior surface 315 by the mandrel 215 of FIG. 2B are not necessarily imparted directly across the entirety of the bearing 200 (e.g. all the way to the other surface 301). Similarly, forces from interface with the well wall 185 which translate over to the exterior surface 301 are not automatically imparted directly across the bearing to the opposite surface 315 (see FIG. 2B).

The intentional physical disconnect between the journal pieces 320, 340 as described above results in an interface 330 that allows for intentional slippage. That is, the reason forces from one surface 301 or another 315 do not necessarily fully translate across the entirety of the bearing 200 is due to the allowance of slippage at the noted interface 330. Once more, this interface 330 is located at an isolated interior of the bearing 200 such that its presence does not result in a new location of exposure in terms of well debris and other corrosives of the environment. More specifically, unlike use of multi-piece spherical bearings for example, a multi-piece bearing 200 is provided in FIG. 3B that does not result in added surface exposure to the well environment that might compromise life of the bearing 200.

Referring now to FIGS. 4A and 4B, alternate embodiments of roller devices 400, 401 are shown which may be of a more elongated 400 or dual-sided 401 configurations. These embodiments highlight the fact that a variety of different configurations of roller devices may be employed which utilize underlying embodiments of cylindrical bearing based mechanisms, whether of a journal bearing type or otherwise.

Specifically, with reference to FIG. 4A, a side view of the toolstring 101 of FIG. 2A is shown, again with focus on the vicinity of the logging device 160 near a sampling tool 465. However, in contrast to FIG. 2A, the embodiment of FIG. 4A reveals roller devices 400 which are of a more interior and elongated configuration with respect to the tool housing 460. That is, as opposed to being more fully exterior the housing 460, the roller devices 400 may be recessed to a degree into the housing 460 (see FIG. 4B).

By the same token, with reference to FIG. 4B, a roller device 401 may instead be extended further away from the housing 460 (e.g. and of a dual-sided configuration). Specifically, FIG. 4B is a front cross-sectional view of the same toolstring 101 of FIG. 4A, taken from line 4-4 thereof. In this view, the internal workings of roller devices 400, 401 are shown. Wear piece type journal bearings 410 of a more elongated variety may serve as the cylindrical bearing based mechanisms as depicted in the partially sectional view of a dual-sided roller device 401.

Additionally, with reference to these same roller devices 401, they may be positioned at opposite sides of the housing 460 and of sufficient distance (d′) relative a diameter (D) of the well 180 so as to provide a degree of centralization. That is, rather than attain a footing at a side of the well 180 opposite the perpendicular axis 411 and zone 466 for the sampling tool 465, centralization above the ‘floor’ of the well wall 485 may be attained. So, for example, at the time of sampling, it is less likely that the elongated interior roller devices 400 would be in contact with debris at the well wall 185, particularly during formation sampling. Of course, a variety of additional tool configurations and roller device types may also be developed which take advantage of underlying embodiments of cylindrical bearing based mechanisms.

Referring now to FIG. 5, a flow-chart summarizing an embodiment of employing roller devices of a toolstring as an aid to conveyance is shown. Specifically, the toolstring is deployed into the well as indicated at 510. The roller device may provide conveyance assistance as indicated at 530. Further, in recognition of debris and other wear-inducing factors of the well environment, a cylindrical bearing based mechanism may be utilized in conjunction with the device as noted at 550. Thus, as indicated at 570 and 590, an application may be performed with the toolstring and it may be removed from the well in a reliable and repeatable manner without undue concern over roller device ineffectiveness, failure or excessive wear.

Embodiments described hereinabove include roller-aided conveyance devices and techniques that may or may not be passive in nature. However, these roller devices avoid the use of ring assemblies utilizing a plurality of spherical bearings. Thus, bearing life is not significantly compromised in light of regular exposure to the downhole environment. Rather, roller devices and conveyance may be aided through use of an underlying cylindrical bearing based mechanism, that may even be of enhanced manufacturability and comparatively low labor replacement cost. In addition to aiding conveyance of the toolstring 101, those skilled in the art will appreciate that the roller device or devices 100, 400, and/or 401 may also prevent or mitigate sticking of the toolstring 101 while the toolstring 101 is stationary, such as when the sampling implement 265 or sampling tool 465 is directly interfacing with the well wall 185 for extended periods of time, as the roller device or devices 100, 400, and/or 401 may provide a mechanism for passively and/or responsively rolling against a well wall 185 and/or a mudcake formed thereon.

The preceding description has been presented with reference to presently preferred embodiments. Persons skilled in the art and technology to which these embodiments pertain will appreciate that alterations and changes in the described structures and methods of operation may be practiced without meaningfully departing from the principle, and scope of these embodiments. Regardless, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope. 

What is claimed is:
 1. A roller device for incorporation into a housing of a downhole toolstring to aid conveyance thereof through a well, the device comprising: a body with an exposed surface for contacting a wall of the well during the conveyance through the well; and a cylindrical bearing based mechanism for disposal at an underside of said body opposite the exposed surface.
 2. The roller device of claim 1 wherein said cylindrical bearing based mechanism comprises a journal bearing.
 3. The roller device of claim 2 wherein said journal bearing is substantially circumferentially monolithic.
 4. The roller device of claim 2 wherein said journal bearing comprises: a first journal piece; and a second journal piece adjacent said first with an isolated slip interface therebetween.
 5. The roller device of claim 1 wherein said cylindrical bearing based mechanism comprises a cylindrical roller bearing for radial and axial slip.
 6. A downhole tool for incorporation into a toolstring and for conveyance through a well, the tool comprising: a housing; and a roller device accommodated by said housing for contacting a wall of the well during the conveyance therethrough, the device comprising a cylindrical bearing based mechanism to allow rolling thereof during the contacting of the wall.
 7. The tool of claim 6 wherein said roller device is of a diameter larger than the toolstring.
 8. The tool of claim 6 wherein the toolstring is between about 50 feet and 150 feet in length.
 9. The tool of claim 8 wherein the well includes a bend to a non-vertical section.
 10. The tool of claim 6 wherein said roller device is one of exteriorly disposed relative said housing, at least partially recessed into said housing and extended from said housing.
 11. The tool of claim 10 wherein the roller device is a first roller device, the tool further comprising a second roller device at an opposite side of said housing relative the first roller device.
 12. The tool of claim 11 further comprising a formation disturbing implement at said housing between said roller devices, said roller devices exteriorly disposed and to provide a foothold at a wall of the well for substantially perpendicular orientation of said implement relative the wall.
 13. The tool of claim 12 wherein said formation disturbing implement is a sampling implement for attaining substantially sealed engagement with the wall during sampling due to the perpendicular orientation.
 14. The tool of claim 11 wherein the roller devices are dual-sided and extended from said housing to promote a degree of centralization of the tool in the well.
 15. A method of conveying a toolstring through a well, the method comprising: deploying the toolstring into the well over a well access line; employing a roller device for assistance in aiding conveyance of the toolstring to a target location in the well; and utilizing a cylindrical bearing based mechanism of the roller device during said employing thereof for conveyance assistance.
 16. The method of claim 15 wherein deploying of the toolstring is a coiled tubing deployment and the well access line is coiled tubing.
 17. The method of claim 15 further comprising performing an application with a tool of the toolstring at the target location.
 18. The method of claim 17 wherein the application is a formation sampling application.
 19. The method of claim 18 further comprising substantially perpendicularly orienting a formation sampling implement of the tool relative a wall of the well for the application with the roller device.
 20. The method of claim 15 further comprising enhancing centralization of the tool in the well with the roller device during the conveyance through the well. 